In the end, spying is a matter of deceit and betrayal, no matter what the perceived justice of the cause for which it is done. Said Rebecca West, the great English journalist and student of history, “Having watched the form of our traitors for a number of years, I cannot think that espionage can be recommended as a technique for building an impressive civilization. It’s a lout’s game.” So it is—and moreover, it’s a game in which the innocent and unaware are all too easily entrapped, a soul-crushing negation of the trust on which a true civilization is founded.

Each of the films in this series speaks to this fact in one way or another, but perhaps none so compellingly as The Spy Who Came in from the Cold. Directed by Martin Ritt and released 45 years ago, in December 1965, in some of the darkest hours of a cold war that threatened to go hot at any moment, the film is largely set in East Berlin, the epicenter of espionage. There a British agent, portrayed by Richard Burton in one of his finest performances, has slipped across the divide of the Berlin Wall, supposedly to defect to the Soviet cause, as so many British intelligence agents were doing at the time. In fact, he has been sent to plant false intelligence, a matter that undoes Burton’s Alec Leamas when he stops to ponder just who is good and who is evil. He explodes, in a tirade that will be familiar to readers of other books by John le Carré, the author of this tale: “What the hell do you think spies are? Moral philosophers measuring everything they do against the word of God or Karl Marx? They’re not! They’re just a bunch of seedy, squalid bastards like me: little men, drunkards, queers, hen-pecked husbands, civil servants playing cowboys and Indians to brighten their rotten little lives. Do you think they sit like monks in a cell, balancing right against wrong?”

They do not, and Leamas has to reckon with the consequences. Though this series has been careful not to rank these films—all twelve are great, but there are many other great spy movies out there—I have no hesitation about claiming this as the single best espionage film ever made.